reading a medical report:
we now know that our brains are very active during sleep and a variety of nerve signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of neurons. the brainstem produces neurotransmitters including seratonin and norepinephrine that can keep certain parts of the brain active while we are asleep. other neurons tend to switch off signals that keep us awake. current research indicates that adenosine builds up in our blood while we are awake and causes drowsiness and that when we sleep this chemical gradually breaks down.
do we really need sleep to survive? i read a book along time ago about a philosopher who refused to sleep. not sure if it was Rousseau.